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United States Patent | 5,280,561 |
Satoh ,   et al. | January 18, 1994 |
Improvements in a method of processing wideband audio signals by a sub-band coding system are provided. Linear codes having frequency components in which audio signal power is concentrated are selected from linear codes separated into a plurality of frequency band components and decoded. The presence or absence of sound in the audio signals is detected by referring to the selected linear codes and/or a gain coefficient is determined. Level control of the decoded linear codes is performed by using the thus determined gain coefficient.
Inventors: | Satoh; Mihoko (Kanagawa, JP); Ebisawa; Hideaki (Kanagawa, JP); Naito; Yushi (Kanagawa, JP) |
Assignee: | Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP) |
Appl. No.: | 750290 |
Filed: | August 27, 1991 |
Aug 28, 1990[JP] | 2-225869 |
Current U.S. Class: | 704/200 |
Intern'l Class: | G10L 005/00 |
Field of Search: | 381/34-40,29-33,46,47 379/158 395/2 |
4811398 | Mar., 1989 | Copperi et al. | 381/37. |
4975657 | Dec., 1990 | Eastmond | 381/46. |
4989246 | Jan., 1991 | Han et al. | 381/40. |
5007093 | Apr., 1991 | Thomson | 381/46. |
5054075 | Oct., 1991 | Hong et al. | 381/36. |
5086471 | Feb., 1992 | Tanaka et al. | 381/36. |
Foreign Patent Documents | |||
63-123257 | May., 1988 | JP. |
"7 kHz Audio-Coding Within 64 KBIT/S", Recommendation G.722 published in CCITT Blue Book, vol. 111-Fascicle 111.4 pp. 269-341, Nov., 1988. "Basic Digital Switching" by Shinichi Aizawa, OHM Co. Ltd., pp. 121-124 (FIG. 2.51), Jan. 10, 1983. |